Original Canonet - Parallax Mirror

[Graemea]

Hi Everyone


I recently purchased a very nice original Canonet. It wasn't a camera I'd really appreciated until I actually bought one. Sure the shutter priority auto mode is a bit clunky, but the feature set is impressive. Full shutter speeds - 1 to 1/500 of a second. Clear rangefinder with parallax adjustment and a reputedly good 45mm F1.9.

The only thing is that something was loose in the finder and the frame lines flopped around. It was easy to open up - only three screws, but when I took the top off the parallax mirror fell out. I can see where it was attached roughly, but not which side of the mirror was glued - silvered side out or in?

So can someone put me straight on this, plus what would be best to re-attach it with? Any advice would be much appreciated. I'm planning to put a B&W film through as soon as I have it sorted.

Many thanks, Graeme

 

[farlymac]

If you look closely you should be able to see some residue from where it was glued before. If you are talking about the rotating mirror then it would be silvered side to the front of the camera. If it's the half-silvered beam splitter the silvered side would face towards the rear of the camera. I use a product called Weldbond to glue mirrors and other glass pieces as it dries clear, and doesn't outgas.


PF

 

[Graemea]

Thanks for that. I've looked really hard at it, but I can't see any old bond marks unfortunately.


Sounds like it should be mirrored side forward then. It's the large moving mirror with the clear rectangle for the rangefinder to pass through.

 

[wwfloyd]

Here's a pic I made of the Canonet 19, to show rangefinder adjustment. Maybe it will help.
Canonet 19 rangefinder adjust by wwfloyd, on Flickr

 

[Graemea]

Thanks, that's very useful.

Looking at it - the large mirror behind the finder mask - it appears to be silvered on the side away from the front of the camera. Would you agree?

It also gives me a good idea of how it should be positioned for gluing.

Thanks again.

 

[wwfloyd]

Thanks, that's very useful.

Looking at it - the large mirror behind the finder mask - it appears to be silvered on the side away from the front of the camera. Would you agree?

It also gives me a good idea of how it should be positioned for gluing.

Thanks again.

Yes, because the viewfinder mask is reflected into the view.


Here's that "same" mirror in a Petri 7s, shown from the front. BTW, I've had that mirror loose in 3 different models of Petri, and, it always gives the appearance of the frame lines shifting as the camera is tilted, just as you described with the Canonet.
Petri 7s rangefinder by wwfloyd, on Flickr

 

[Graemea]

Hi again,


but on the Petri it looks like the side facing the front of the camera is silvered... Or am I wrong?


Now I'm confused, but I'm wondering if it really makes much difference?


Cheers, Graeme

 

[wwfloyd]

Hi again,


but on the Petri it looks like the side facing the front of the camera is silvered... Or am I wrong?


Now I'm confused, but I'm wondering if it really makes much difference?


Cheers, Graeme

I think we're just mixing terms. Silvering on a mirror is on the back side! Also, note that the dull silvering gives a surface that can take adhesive better than the reflective glass side. Dull side gets the glue; shiny side reflects the image.


Yes, it make a difference.

 

[Graemea]

Weirdly, the Canonet mirror is equally reflective both sides. You can only tell which side is which by looking at the edge.


I'm used to mirrors that have an opaque surface on top of the silvering which is on the back. So I'm still confused...

 

[Dan Daniel]

Put a toothpick on the surface. On the front surface side, the tip of the toothpick and the reflection will be at the same point no matter how you move around. On the rear surface side, you'll get parallax shifts between the toothpick tip and its reflection as you move.


Once you do this, it should be pretty clear.

 

[wwfloyd]

Weirdly, the Canonet mirror is equally reflective both sides. You can only tell which side is which by looking at the edge.
...

Ah, interesting. Sounds like they sandwiched the silvering between 2 layers of glass.

 

[Graemea]

Well...

I'm still confused which side should face the front of the camera?

Its a mirror either way, but one is on the front of the glass (I think SLR mirrors are front silvered) the other is on the back - the way I thought the original Canonet photo above appeared.

The mirror in the Petri photo appears to me front silvered but my eyesight is not that good.

Which is it?

 

[retinax]

I think we're just mixing terms. Silvering on a mirror is on the back side! Also, note that the dull silvering gives a surface that can take adhesive better than the reflective glass side. Dull side gets the glue; shiny side reflects the image.


Yes, it make a difference.

On a bathroom mirror, yes, the silvering is on the back. In cameras it's often on the front.
I'm not certain about this one but I think silvering forward more likely. If you were to put glue on the silvered side and it somehow comes loose again, chances are the silvering would come off the glass and the mirror would be trashed.
OP, just put the thing in silvering forward, then check if you can see the frame lines sharply. That's the only thing that might depend on the orientation, all this mirror does is bringing them into view.
Only use very little glue, you or someone else might need to take it out again at some point!

 

[Dralowid]

On a Hanimex Automatic (!) that happens to be on my desk in bits the silvering is forward facing. I know this because it is scratched on one corner.

Whatever happened to Hanimex???

 

[Dan Daniel]

I think we're just mixing terms. Silvering on a mirror is on the back side!

No. Silvering can be on the back side or on the front side. Back surface or front surface mirrors.

https://www.tmf.uk.com/products/why-use-front-surface-mirrors

And to the OP, yes, it makes a difference. Back surface mirrors will give a double image. For frame line projection like in a rangefinder camera, this might be so subtle as to be barely visible. But no chance risking it. Put it front surface facing out.

 

[Dan Daniel]

Well...

I'm still confused which side should face the front of the camera?

Its a mirror either way, but one is on the front of the glass (I think SLR mirrors are front silvered) the other is on the back - the way I thought the original Canonet photo above appeared.

The mirror in the Petri photo appears to me front silvered but my eyesight is not that good.

Which is it?

Front surface.

Step back and take a breathe. This is not that difficult. Toothpick on surface will show you if it is the front or the back surface. Put glue on the back surface and have front surface face to the frameline window and to the viewfinder semi-silvered splitter. It's a simple reflection process. No lenses, etc.

 

[wwfloyd]

No. Silvering can be on the back side or on the front side. Back surface or front surface mirrors.

https://www.tmf.uk.com/products/why-use-front-surface-mirrors

And to the OP, yes, it makes a difference. Back surface mirrors will give a double image. For frame line projection like in a rangefinder camera, this might be so subtle as to be barely visible. But no chance risking it. Put it front surface facing out.

Well, this is interesting, and appreciated.

I will note, though, that my frame of reference was my 3 Petri models (7s, Racer, Color 35) that needed the mirrors re-attached. I had the advantage of being able to see their original position. I remember 'for sure' that at least one was mirrored on the back.

Or, let me ask this: is it possible that Petri did silver the front, but also put a coating of something on the back, that I have mistaken for silvering? I'm thinking that must be the case.

 

[Mackinaw]

Not the same, but this may be of help. A few years back I had to rebuild the rangefinder on an old Busch Pressman 4x5. The glue holding the mirror in place had deteriorated and the mirror was flopping around inside the housing. I wasn’t sure which way it went in, so used a dab of rubber cement to hold the mirror in place as I figured things out. Once fixed to my satisfaction, I used glue to hold it in place. Maybe try this too.

Jim B.

 

[Graemea]

To everyone who posted, thanks very much.

I think I'll go with it front side coated forward then. Now to find that glue.

Cheers

Graeme

 

[Dan Daniel]

Or, let me ask this: is it possible that Petri did silver the front, but also put a coating of something on the back, that I have mistaken for silvering? I'm thinking that must be the case.

Without seeing the specific design, it's hard to know exactly what was at stake? Basically if you are trying to maintain an image of some sort, front silvering is the way to go. But if you are simply bouncing light, maybe it doesn't matter? Or it could be that the problem that comes in back surface mirrors reflecting an image were so minor in that usage that back surface was easier?

The problem with front surface mirrors is that the silvering is right out there naked to the world. With back surface you can put a protective material behind the silvering. And tarnish will not form since the silver surface is protected. Old front surface mirrors are subject to tarnish.Modern film deposition mirrors can have another material applied on top that maintains the optical properties but prevents tarnishing and easy scratching.


The toothpick test is very effective for determining front or back surface silvering.